1. Field of the Invention
This invention relates, in one of its aspects, to a process for the preparation of ortho-methyl anilines from ortho-amino benzyl sulfoxides. Other aspects of the invention relate to novel intermediate quaternary salts and to a process for forming those quaternary salts.
2. Description of the Prior Art
Sulfoxides of the general formula RSOR are known to undergo rearrangements under acid conditions to produce alpha-substituted sulfides, the overall result being reduction of the sulfoxide group and oxidation of the adjacent carbon atom. Reactions of this type are generally known as the Pummerer reaction. The products of such Pummerer reactions when acid halides are employed normally include alpha-substituted halomethyl sulfides, or via hydrolysis, the corresponding aldehydes. Russel & Mikol, Mech. Mol. Migr., 1, 157-207 (1968).
In the preparation of certain aniline derivatives useful as herbicides, various methods have been developed, for example, for the reduction of ortho-methylthiomethyl anilines or ortho-methylsulfinylmethyl anilines to ortho-methyl anilines. Once such reaction involves use of the prior art direct hydrogenation of the sulfide in the presence of a catalyst such as Raney nickel. Use of Raney nickel for desulfurization, however, requires substantial amounts of catalyst, special equipment and special handling.
While use of an ortho-amino benzyl sulfoxide as a starting material to produce anilines can be attractive, particularly when the aniline contains other ring substituents, the presence of sulfur in the starting material is detrimental if hydrogenation employing metal hydrogenation catalysts, such as noble metal catalysts, is contemplated.
It is an object of this invention to provide a process for the conversion of ortho-amino benzyl sulfoxides to ortho-methyl anilines in high yields.
It is a further object of this invention to provide a process for the conversion of ortho-amino benzyl sulfoxides to ortho-methyl anilines that includes an effective separation of sulfur by-products.
It is a still further object of this invention to provide a process for the conversion of ortho-amnio benzyl sulfoxides to ortho-methyl anilines that does not include any potentially hazardous process step.
It is another object of this invention to provide a process for the conversion of ortho-amino benzyl sulfoxides to ortho-methyl anillines that employs only readily available reagents.
It is also another object of this invention to provide a useful process for the conversion of anilines derived from sulfilimine rearrangement to ortho-methyl anilines.
It is still another object of this invention to provide stable quaternary ortho-amino benzyl ammonium halide salts.
It is yet another object of this invention to provide a process for the conversion of ortho-amino benzyl sulfoxides to stable quaternary ortho-amino benzyl ammonium halide salts.